Fuse



Nov. 30, 1954 M. FlscHl-:R

FUSE

Filed Oct. 29. 1952 2 Sheets-Sheet l 75 5,4 INVENTOR Naw? y ,f/scf/ff?,

NOV. 30, 1954 M, FlSCHER 2,695,937

FUSE Filed om. 29, 1952' 2 sheets-sheet 2 TIE- l :PLIS 14:.

United States Patent O FUSE Murry Fischer, New York, N. Y.

Application October 29, 1952, Serial No. 317,415

Claims. (Cl. 200-124) The invention relates to fuses for electrical circuits and has special reference to a fuse of the screw type wherein the fuse is of substantially cylindrical form and is screwed into a socket.

More particularly the invention relates to a renew able fuse wherein, after each interruption of the current caused by overloading the circuit and the blowing of the fuse, the latter may be restored by simple manual movement to again establish the circuit.

One important feature of the invention is to provide a device of this character wherein the blowing of the fuse will have practically no deleterious effect upon the fuse material.

A second important object of the invention is to provide an improved fuse of this character having extremely long life.

A third important object of the invention is to provide a spring-operated renewable fuse wherein the action of the spring will take place after the blowing of the fuse and will automatically reset the fuse.

A fourth important object of the invention is to provide a renewable fuse of this character wherein, after effective operation by the spring, the latter may be reset to again operate upon the next blowing of the fuse, resetting of the spring, re-establishing the circuit.

With the above and other objects in View, as will be hereinafter apparent, the invention consists in general of certain novel details of construction and combinations of parts hereinafter fully described, illustrated in the accompanying drawings and particularly claimed.

In the accompanying drawings like characters of reference indicate like parts in the several views, and:

Fig. l is a vertical axial section through a fuse constructed in accordance with this invention and showing the conditions after the fuse has blown and before it has been reset.

Fig. 2 is a view similar to Fig. 1, but showing the conditions in the fuse upon the springs being set for effective operation.

Fig. 3 is a section on the line 3-3 of Fig. 1.

Fig. 4 is a section on the line 4-4 of Fig. l.

Fig. 5 is a view similar to Fig. 4, but with certain parts removed.

Fig. 6 is a section on the line 6-6 of Fig. 1.

7 is a side elevation of the arrangement shown in Fig. 8 is a bottom plan view of Fig. 7.

f Fig. 9 is a detailed plan view of a shaft used in this use.

Fig. 10 is a detailed view partly in section and taken from the right side of Fig. 9.'

Fig. 11 is a section on the line 11--11 of Fig. 9.

Fig. l2 is a section on the line 12-12 of Fig. 9.

Fig. 13 is a View similar to Fig. 1 but showing a modified form of the invention, the view being a section on the line 13-13 of Fig. 15.

F Fig. 14 is a view of this modified form similar to Fig. 15 is a plan view of this modiiied form.

Fig. 16 is a section on the line 16-16 of Fig. 13.

Fig. 17 is a section on the line 17-17 of Fig. 13.

Fig. 18 is a section on the line 18-18 of Fig. 13.

In each of the forms of the invention, as here illustrated, there is provided a casing indicated in general at 10. This casing is of insulating material and has an upper section 11 and a lower section 12. The lower sec- 2,695,937 Patented Nov. 30, 1954 tion is provided with a bottom 13 having a depressed central portion. The upper section has a top portion 14 formed thereon, and this top portion is provided with a diametrically disposed slot 15 for purposes presently to be described. The casing thus has a cylindrical side wall, a bottom and a top.

A screw threaded conductive shell 16, which is adapted to be screwed into a standard fuse plug socket, is fitted on the lower part of the casing side wall. A contact button 17 is secured to the central part of the bottom 13 so that it extends through the bottom and has an external and internal portion.

As shown in Fig. 5, the casing is provided at its side wall at the bottom with opposed inward projections 18 and 19, each of which has a bearing socket 20. The bearing sockets 20 are in alignment and receive the ends of an electrically conductive shaft 21. The ends are journalled in the sockets but the shaft is restrained from rotation by means of a metallic fusible binder block 23. The projecting portion 19 is provided with a square or non-circular socket 22 that is aligned with and disposed inwardly of the bearing socket 20 in such projection. The block 23, which is also square or at least non-circu lar, is positioned in such socket 22 and, thus, when hard, is unable to rotate. The block, when cool and hard, ixedly embraces the shaft 21 and the shaft cannot rotate. Fixedly circumposed on the shaft is a ratchet wheel 25, which is formed from suitable electrically conductive material.

As shown in Figs. l to 12, one end of a metallic leaf spring 26 is fastened to the button 17 and the spring upstands from the bottom 13. Thus, the spring extends from the bottom axially of the casing and has a reverted U-shaped upper free end which extends at its web portion through the slot 15. The upper end of the spring has a downwardly bent free leg 26, which extends toward the bottom 13 and terminates in an offset lip 27. The lip 27 is engageable with the teeth of the ratchet to lock the spring in engagement with the ratchet. A non* conducting reset cap 27 is fitted on the web portion of the upper end and embraces the upper end. A lateral outwardly extending shoulder 28 is formed on the open, lower end of the cap and is engageable with the underside a the top 14 to prevent loss of the cap through the s ot In the form of the invention shown in Figs. 13 to 18, inclusive, the main body of the device is constructed in the same manner as that of the first form except that the slot 15 of the top 14 has a centrally disposed circular opening 15 substituted therefor. Also, the spring 26 of the rst form is modified to provide a spring having an upstanding portion 26a which curves toward the center and merges into a rebent portion 26b fitted in a push button 27a. From the free extremity of the rebent portion, the spring extends laterally toward the wall 11 as at 26e and is then bent downward to provide an arm 27b having a terminal hook for engagement with the ratchet wheel 25. As shown in Fig. 14 depression of the push button will bow the portion 26a of the spring and the portion 27b will slide downwardly until the terminal hook can engage to meet one of the teeth of the ratchet, whereupon, when pressure is removed from the push button, the ratchet will be rotated by the upward movement of the spring portion 27b, this being effected by the straightening of the bowed part of the spring.

In operation, let it be assumed that the parts are in the position of Fig. 2 and that the fuse has been screwed into a. socket for forming ratchet connections. Under such clrcumstances current will tow from the button 17 through the spring 26 and its parts 26 and 27, through the ratchet 25, shaft 21, fusible block 23, lip 24 and shell 16. Upon the circuits being sutliciently overloaded, the fusible block 23 will soften. The seating of this block in the socket 22 has, while the block is hard, prevented rotation of the shaft. Whenever the block softens sufficiently, the shaft will then rotate under the influence of the spring and this rotation will permit the spring to disengage the ratchet and the parts to assume the positions shown in Fig. l. There will then be no current passing through the block 23 and in consequence this block will again freeze and hold the shaft from rotation. The userof the fuse may then push the cap 27 back to the position shown in Fig. 2, whereupon the fuse willl be reset until again overloaded. Obviously, if the overloaded condition persists, the user will be at once informed thereof: because each time the circuit is restoredL and the user removes his finger from the cap, thefuse will re-open.

What is: claimed, is.:

l. In afuse adapted to be inserted ina fuse plug socket, a nonconductive casing having a side wall, a top. and a bottom, a screw threaded conductive shell iitted on the lower par-t of the side wall of the casing, a contact button extending through, the casing bottom, an electrically conductive shaft mounted for,V rotationy within the casing and extending transversely thereof, a metallic fusible member in saicl casing and having an opening receiving one end of the shaft and fitting tightly on= said end of said shaft to hold the shaft against rotation, said member having conductive connection with the shell, and an electrically conductive resilient, member attached tothe button and extending upwardly to the top ofthe casing, an insulative cap on` the extending upper end of the member for mov ing the member,v manually toward the shaft, an electrically conductive ratchet ixedly circumposed on the shaft and an extension on saidV member lockingly engageable with the teeth of the ratchet under manual positioning thereof and tensioning of the member to establish an electrical conductive path from the button to the shell which, when overloaded, will effect a fusion of the fusible block whereby the ratchet is rotated by the member and releases the member to. interrupt the conductive path.

2. A fuse of the type adapted to be inserted in a fuse plug socket comprising, a non-conductive casing having a side wall, a top and a bottom, a conductive shell secured on a portion of the side wall and having means for mounting it in a, fuse plug socket, a contact button extending through the bottom of the casing, an electrically conductiveV shaft mounted for rotation transyersely of the casing and having its ends journalledin opposing portions of the interior of` the side wall of the casing, an electrically conductive ratchet wheel fixedly circurnposed on the shaft, a fusibley member of conductive material tightly embracing the shaft and disposed in electrical conductive engagement with the shell, means for mounting said fusible member in the casing so that the shaft is held against rotation when the fusible member is cool and hard, a resilient electrically conductive strip connected at one end to the contact button and extending axially in the casing to the top, an insulative cap on the extending end of the strip for manually flexing the strip. toward the shaft, a hook extension on said strip lockingly engageable with the teeth of the ratchet wheel when t-he'strip is exed toward the shaft, said hook extensionholding the strip in such flexed position and in electrical contact with the ratchet whereby an electricaly conductive path from the button to the shell is established and whereby upon current overload, the fusible member will be fused to permitl the shaft and ratchet wheel to rotate under the urgement of the resilient member which, as the ratchet wheel rotates frees the hook extension from engagement with the ratchet wheel to interrupt the Conductive path from thel button to the shell.

3- A fuse as. claimed in Claim 2;, wherein Said fusible. member when cool is non-circular and. is socketed in, a non-circular recess in the casing andis circumposed tightly O11 the Shaft t0 provide the means for holdingthe., Shaft against rotation.v

4. A fuse as claimed in claim 3,y wherein said` casing has bearing Sockets journallingfthe ends of the Shaft-1 Said;

non-circular recess being termed inwardly Ot Qn f Said bearing sockets.

5. Al fuse as claimed in @121ml wherein Said tgp-,has

an aperture receiving said insulative cap.

References Cited in the filel Qff this Patent UNITED STATES `PArEisrrs 

